Swamp crab spider
This crab spider's front two leg pairs turn almost black, a striking contrast against its pale, ochre body and low, damp grassland home.
| Where | Damp grassland, fens and wetland |
|---|---|
| Size | Female 5 to 8.3 mm, male 3 to 4 mm body length |
| When | April to October |
The Swamp crab spider has a light brown to pale yellow body marked with a darker triangle and side stripes, while the femur and patella of its first two leg pairs are noticeably blackish, more so in males.
It waits among low, damp vegetation in fens and wet grassland, ambushing small insects rather than spinning a web to catch them. It ranges from lowland wetlands up into alpine meadows across its range.
Traits
Habitat
Wetland
Colour
Brown, Yellow, Black
Active
Day and night
To people
Not dangerous to people; this small ambush hunter of damp grassland and fens has no history of biting people.
Activity through the year
Often confused with
Xysticus cristatus has paler, more evenly coloured legs, lacking the blackish patella and femur on the first two leg pairs that mark the Swamp crab spider.
Questions
Is the Swamp crab spider dangerous to people?
Not dangerous to people; this small ambush hunter of damp grassland and fens has no history of biting people.
When can you see the Swamp crab spider?
The Swamp crab spider can be seen from April to October, by day and at night.
Plate retouched from a museum specimen photo by Staatliche Naturwissenschaftliche Sammlungen Bayerns, CC BY 4.0, GBIF Licence
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Last updated 2026-09-27. Every entry is checked against published sources.